Liquid crystal motion picture projector with memory

ABSTRACT

A liquid crystal moving picture projector (1) includes a liquid crystal imager (2) for creating characteristics of an image, and projection optics (3) for projecting images sequentially created by the imager, the imager including a liquid crystal material (4) capable of temporarily storing information at respective areas thereof to create image characteristics capable of being projected sequentially by the projection optics. The temporary storage may be a function of charge storage directly on liquid crystal material or by structural storage characteristics relying on bulk effect of smectic liquid crystal. A method of projecting plural images in sequence includes creating an image or characteristics of an image in a liquid crystal material, storing such image in such liquid crystal material, directing light at such liquid crystal material, projecting such image as a function of light transmitted through or scattered by such liquid crystal material, and creating a further image in such liquid crystal material for subsequent projection.

This application is a continuation-in-part of applicant's U.S. Pat.application Ser. No. 892,497, filed Aug. 1, 1986, U.S. Pat. No.4,693,557, which is a continuation-in-part of applicant's U.S. Pat.applications Ser. No. 585,884, filed Mar. 2, 1984, now U.S. Pat. No.4,603,945, issued Aug. 5, 1986, and Ser. No. 608,135, filed May 8, 1984,now U.S. Pat. No. 4,613,207, issued Sept. 23, 1986. The entiredisclosures of such patent applications hereby are incorporated byreference.

CROSS REFERENCE TO RELATED APPLICATIONS

Reference is made to applicant's commonly assigned, U.S. Pat. Nos.4,435,047, issued Mar. 6, 1984, for "Encapsulated Liquid Crystal andMethod"; U.S. Pat. No. 4,606,611, issued Aug. 19, 1986, for "EnhancedScattering in Voltage Sensitive Encapsulated Liquid Crystal"; U.S. Pat.No. 4,616,903, issued Oct. 14, 1986, for "Encapsulated Liquid Crystaland Method"; U.S. Pat. No. 4,662,720, issued May 5, 1987, for "ColoredEncapsulated Liquid Crystal Devices Using Imbibition of Colored Dyes andScanned Multicolor Displays"; U.S. Pat. No. 4,596,445, issued June 24,1986, for "Colored Encapsulated Liquid Crystal Apparatus Using EnhancedScattering"; and Ser. No. 585,883 for "Encapsulated Liquid CrystalMaterial, Apparatus And Method", filed Mar. 2, 1984; the entiredisclosures of such patents and applications hereby are incorporated byreference.

TECHNICAL FIELD

The present invention relates generally to projectors and, moreparticularly, to a liquid crystal moving picture projector and method.In one embodiment of the invention light incident on a liquid crystaldisplay-type device or imager selectively is scattered or transmitted byrespective portions of the liquid crystal display, and a projectionmechanism projects an image formed by either such scattered light orsuch transmitted light. (As used herein in connection with the inventionthe terms liquid crystal display and liquid crystal imager are intendedto be synonymous and equivalent).

BACKGROUND

A conventional optical moving or motion picture projector may include alight source, an input image device holder, such as a film guide,sprockets, shutter, etc., or by which a film, and particularly theframes thereof, may be placed for illumination by light from the lightsource, and a lens system for projecting an image of the illuminatedframe. Typically the film would have optically transparent portions andoptically absorbent portions, e.g., black and/or colored portions. Whenprojected onto a screen, such black portions appear black due toabsorption of light by the light absorbing, e.g., black emulsion,material, and the optically transmissive portions would appearrelatively bright on the screen. Common exemplary projectors are of 8,16, and 32 millimeter sizes, depending on the size of the film used.

One problem with conventional projectors is the large amount of heatthat is absorbed by the light absorbing portions of the film, whichcould cause destruction or damage to the film; to minimize such heatbuild-up it often is necessary to use one or more infrared or heatabsorbing filters optically upstream of the film. The heat dissipated inthe heat filters and at the optical source or cabinet containing thesame requires elimination, for example by a blower or other means. Theblower may produce undesirable noise and/or vibration and uses energythat would not have to be consumed if the heat did not require suchelimination. A further disadvantage of conventional projectors is thediffraction of light at the interface between light absorbing material,such as a black emulsion, and transparent material of the film; suchdiffraction can reduce the contrast and quality of the projected imageseen on a screen. Furthermore, in conventional film projectors, contrastwould be reduced since images are formed in part, at least, by theblockage of light, and such blockage is a function of absorption, whichcan vary, depending on the quality of opaqueness of the blockingmaterial. Other disadvantages of conventional motion picture projectorsis the size and number of reels of film needed to project an entiremotion picture, story, etc., due to the relatively fixed nature of therespective images and scenes in the film.

Liquid crystal material currently is used in a wide variety of devices,including, for example, optical devices such as visual displays. Aproperty of liquid crystal material enabling use in visual displays isthe ability to scatter and/or to absorb light when the liquid crystalstructure is in a random alignment and the ability to transmit lightwhen the liquid crystal structure is in an ordered alignment.

Frequently a visual display using liquid crystal material displays darkcharacters on a gray or relatively light background. In variouscircumstances it would be desirable, though, using liquid crystalmaterial to be able to display with facility relatively brightcharacters or other information, etc. on a relatively dark background.It would be desirable as well to improve the effective contrast betweenthe character displayed and the background of the display itself.

Examples of electrically responsive liquid crystal material and usethereof are found in the above patents and applications.

Currently there are three categories of liquid crystal materials, namelycholesteric, nematic and smectic. In one embodiment of the presentinvention nematic liquid crystal material, a combination of nematic andsome cholesteric type or smectic type is used. More specifically, theliquid crystal material preferably is operationally nematic oroperationally smectic, i.e. it acts generally as nematic or smecticmaterial and not as the other types. Operationally nematic means that inthe absence of external fields structural distortion of the liquidcrystal is dominated by the orientation of the liquid crystal at itsboundaries, e.g. with a surface, such as the surface of a capsule-likevolume, rather than bulk effects, such as very strong twists as incholesteric material, or layering as in smectic material. Thus, forexample, chiral ingredients which induce a tendency to twist but cannotovercome the effects of boundary alignment still would be operationallynematic. Such material should have a positive dielectric anistropy.Although various characteristics of the various liquid crystal materialsare described in the prior art, one known characteristic is that ofreversibility. Particularly, nematic liquid crystal material is known tobe reversible (and that characteristic is desirable in the presentinvention), but cholesteric material ordinarily is not reversible.

In another embodiment of the invention smectic or operationally smecticliquid crystal material or a combination of liquid crystal materialsthat operate as smectic liquid crystal material may be used. Acharacteristic of smectic liquid crystal material making it useful inthe present invention is structural storage or memory capability of suchmaterial, i.e., the ability to retain a particular alignmentconfiguration until specifically reset to another alignmentconfiguration. Another characteristic is the responsiveness to electricfield to align with respect thereto.

It is also known to add pleochroic dyes to the liquid crystal material.One advantage to using pleochroic dye with the liquid crystal materialis the eliminating of a need for a polarizer. However, in the nematicform a pleochroic device has relatively low contrast. In the pastcholesteric material could be added to the nematic material togetherwith the dye to improve contrast ratio. See for example the White et alarticle in Journal of Applied Physics, Vol. 45, No. 11, Nov. 1974, atpages 4718-4723. However, although nematic material is reversible,depending on whether or not an electric field is applied across thesame, cholesteric material ordinarily would not tend to its originalzero field form when the electric field would be removed and thischaracteristic may detrimentally affect the quality of a display thatuses nematic and cholesteric liquid crystal and pleochroic dye. Forexample, a disadvantage to use of pleochroic dye in solution with liquidcrystal material is that the absorption of the dye is not zero in thefield-on condition; rather, absorption in the field-on condition followsan ordering parameter, which relates to or is a function of the relativealignment of the dyes.

Usually liquid crystal material is anisotropic both optically(birefringence) and, for example in the case of nematic material,electrically. In optically anisotropic liquid crystal material there isa difference between the ordinary index of refraction and theextraordinary index of refraction the liquid crystal material. Theoptical anisotropy is manifest by the scattering of light when theliquid crystal material is in random alignment, and the transmission oflight through the liquid crystal material when it is in orderedalignment. The electrical anisotropy may be a relationship between thedielectric constant or dielectric coefficient with respect to thealignment of the liquid crystal material.

In the past, devices using liquid crystals, such as visual displaydevices, have been relatively small. Use of encapsulated liquid crystalsdisclosed in applicant's above mentioned patents and co-pendingapplications has enabled the satisfactory use of liquid crystals inrelatively large size displays, such as billboards, etc., and anotherlarge (or small) scale use may be as an optical shutter to controlpassage of light from one area into another, say at a window orwindow-like area of a building. The present invention relates toimprovements in such encapsulated liquid crystals using the same as adevice on which plural frames can be created to represent an image orcharacteristics of an image and to the utilization of the lightscattering and transmitting characteristic of the liquid crystalmaterial for projection purposes.

As used herein with respect to the present invention, encapsulatedliquid crystal material means liquid crystal material in a containmentmedium with a surface for distorting the natural structure of the liquidcrystal in the absence of a prescribed input to cause scattering ofincident light. Thus, a quantity of liquid crystal material is containedin a volume or volumetric space in the containment medium. Therespective volumetric spaces may be substantially closed, may becapsule-like, may be like cells in stable emulsion or matrix, and/or maybe interconnected with other volumetric spaces, and so on. According toa preferred embodiment, the encapsulated liquid crystal material isrepresented by a plurality of volumes of liquid crystal in a containmentmedium formed as an emulsion of the liquid crystal material and thecontainment medium. Such emulsion should be a stable one. Variousmethods for making and using encapsulated liquid crystal material andapparatus associated therewith are disclosed below and in applicant'spatents and co-pending patent applications, which are incorporated byreference.

Liquid crystal projectors and projection optics are disclosed inapplicant's above-mentioned U.S. Pat. No. 4,613,207. Liquid crystalimagers which create an image or characteristics of an image usingcharge storage techniques are disclosed in applicant's above-mentionedU.S. Pat. No. 4,603,945. The present invention relates to a liquidcrystal motion or moving picture projector utilizing such projectors andprojection optics and charge storage and other imager techniques, and/orstructural storage imager techniques to create a plurality of images orcharacteristics of images capable of sequential projection by theprojector. Structural storage imager technique relies on the ability ofthe liquid crystal to maintain or to store a particular alignment ofliquid crystal structure until a further input, such as heat (orthermal, the two terms being used equivalently herein) or electricalinput, is applied thereto.

As used herein, the terms liquid crystal display and liquid crystalimager are intended to be equivalent and interchangeable. The liquidcrystal display or imager creates the image or the characteristics ofthe image intended to be projected by the projector or projectionoptics.

BRIEF SUMMARY OF INVENTION

Essentially the invention relates to a moving piece of liquid crystalmaterial that can produce an image, information or a set of informationto establish characteristics of an image (image, information, and seetof information, etc. being used interchangeably herein) capable of beingprojected such that while the image at one part of the piece of liquidcrystal material is being projected, an image can be put on another partof the liquid crystal material for subsequent projection. Such proceduremay be repeated to provide a series of images that can be sequentiallyprojected to provide the appearance of motion and other effectscharacteristic of a motion picture. Moreover, such image can be writtenonto the liquid crystal material in real time just prior to projectionof the image or may be stored for a period of time, depending oncircumstances, and in the usual case the liquid crystal material wouldhave multiple areas at each of which a plurality of images would bewritten at different times for sequential projection. The images may bestored by relying on electrical charge storage on the liquid crystalmaterial and/or by relying on structural storage characteristics of theliquid crystal material itself. The liquid crystal material may serve asa mechanical transfer medium that both receives and stores the image andtransfers the image into projection optics for projection of the image.

Briefly, the motion picture projector of the invention includes aprojector or projection optics for projecting an image, a liquid crystalmember (sometimes referred to below as a device, film or disk) having acapability of at least temporarily storing characteristics of an imagefor projection, and an input device for selectively applying input tothe liquid crystal member to create a desired image.

In one embodiment of the invention the liquid crystal member is writtento or on electrically to create characteristics of an image, e.g., byapplying electrical charge for temporary storage by the liquid crystalmember; and such image characteristics may dissipate naturally and/ormay be eliminated by dissipation or removal of such electrical charge.

In another embodiment electrical charge may be used to write to or onthe liquid crystal member to create characteristics of an image; andsuch image characteristics may be dissipated or removed by applying heat(or thermal energy) to the liquid crystal member.

In a further embodiment an electrical input may be used to erase theliquid crystal member; and, thereafter, heat energy may be selectivelyapplied, e.g., by laser techniques, to write to or on the liquid crystalmember.

An input device selectively applies appropriate inputs, e.g. electricalor thermal, to the liquid crystal member to create plural image framesthat can be moved sequentially into the projection optics which in turnprojects the frames sequentially. To create a given image frame, theinput is applied to selected areas of the liquid crystal member todetermine which areas of the liquid crystal film will scatter light andwhich areas will transmit light without scattering. After a given framehas been projected, it is moved out of the projection optics and thenext frame is moved into the projection optics for projection. Moreover,preferably after a frame has been projected and moved out of theprojection optics and prior to the next input being applied to suchframes, the remnants of the original input are removed or eliminated.

The projection optics may include an aperture intended to blockscattered light and to transmit light which is essentially transmittedthrough the liquid crystal member for focusing and/or projection onto ascreen or other surface on which the projected image is formed.Alternatively, the projection optics may include a mask which blocks thetransmitted light and a lens which gathers or collects the scatteredlight for projection onto the screen as the viewable projected image.

The liquid crystal member or "film" used in the invention may be anendless strip or loop of film formed of a flexible transparent supportand encapsulated liquid crystal.

In another embodiment the liquid crystal member may be a disk of liquidcrystal material in a containment medium. Such disk may be relativelyrigid or relatively flexible. Moreover, such disk may include the samecomponents as the flexible strip mentioned above. It will be appreciatedthat other types of liquid crystal members also may be used according tothe present invention for the purpose of creating characteristics of animage capable of being projected, one example would be an oscillatingcell or piece of liquid crystal material having two areas on whichinformation may be written--one area would be aligned for projection ofinformation thereon while information is written to the other area andthen the second area would be projected while the first area isrefreshed or rewritten.

Such liquid crystal member, then, in a sense is a liquid crystal displayor imager that has formed therein one or more image frames capable ofsequential projection by the projection optics.

The liquid crystal display taking the place of the transparency orconventional film in the projector of the invention preferably has theability to effect scattering, preferably generally isotropic scattering,of light or to transmit light. In one embodiment the display is formedof plural volumes of liquid crystal material in a containment medium.Those volumes may be fluidically isolated or interconnected or both.

According to the invention, the liquid crystal material in thecontainment medium preferably has two principal conditions or modes ofoperation as a function of alignment of liquid crystal structure withinthe containment medium. In one alignment condition the liquid crystalstructure is distorted from the straight line structure usually taken onby the liquid crystal material when not confined or distorted by asurface, wall, etc. In the other alignment condition the liquid crystalmaterial is in such straight line configuration. Such structures,interaction of the liquid crystal material with the containment mediumto achieve the distorted structure condition, and response of the liquidcrystal material to a prescribed input, such as an electric or magneticfield, to achieve a parallel aligned condition overcoming distortingforces of the containment medium are described in the above-mentionedpatents and applications.

Moreover, operation of such liquid crystal material in a containmentmedium for transmitting or scattering light also is described in detailin such above-mentioned patents and applications. Summarizing suchoperation here, for transmitting light through a particular part of theliquid crystal member or display, the liquid crystal material in thecontainment medium forming that part of the member preferably is alignedgenerally in parallel with the direction of incident light and preferredlight transmission; and the ordinary index of refraction of such liquidcrystal material is selected to be at least substantially the same asthe index of refraction of the containment medium. The liquid crystalmaterial and containment medium may be optically transparent. Since thelight does not experience changes in index of refraction duringtransmission through the containment medium and liquid crystal material,it is transmitted without refracting, bending, scattering, etc.

On the other hand, when the liquid crystal structure is in the mentioneddistorted alignment condition, incident light tends to be scatteredrather than directly transmitted. Such scattering is due to theselecting of the extraordinary index of refraction of the liquid crystalmaterial to be different from the index of refraction of the containmentmedium and the preferred non-flat shape of the containment medium wallsbounding or confining the liquid crystal material. Such scatteringfurther is enhanced due to changes in index of refraction of the liquidcrystal material through a volume thereof, as the degree of distortionand shape of liquid crystal structure through the volume of liquidcrystal material would be expected to be generally non-uniform.

Preferably the encapsulated liquid crystal material is nearly completelyisotropically scattering when in distorted or curvilinear alignment; atleast such liquid crystal material preferably effects as much isotropicscattering as is possible. Isotropic scattering means that when a beamof light enters the liquid crystal material there is virtually no way topredict the exit angle of scattered light. Alternatively, the distortedencapsulated liquid crystal material may effect generally forward, butgenerally random or uncollimated or unfocused forward scattering oflight. On the other hand, in the parallel aligned condition, theencapsulated liquid crystal material effectively becomes opticallytransparent.

The liquid crystal may include pleochroic dye, e.g., cooperative inguest-host relation, if absorption characteristics are desired. Theliquid crystal and/or the containment or support medium may includenonpleochroic dye for coloring light transmitted therethrough. A liquidcrystal color filter having only one color or multiple colors may beused to color light projected by the projector.

As it is used herein with respect to the invention, the terms distortedalignment, random alignment, curvilinear alignment and field-offcondition mean essentially the same thing; namely, that the directionalorientation of the liquid crystal molecules or structure is distorted toan effectively curved configuration. Such distortion is effected, forexample, by the wall of respective volumes or capsules containing theliquid crystal.

On the other hand, as it is used herein with respect to the invention,parallel aligned, ordered alignment, and field-on condition means thatthe liquid crystal material in a volume, capsule, etc., is generallyaligned in parallel, for example with respect to a currently orpreviously applied electric field.

The present invention provides the ability to produce relatively rapidlyan image of alphanumeric, graphical, pictorial, etc., data, information,images, etc., from information received from a remote source and/or froma local source. Importantly, the invention permits the formation of animage in real time or substantially in real time, e.g., essentiallyimmediately on receipt of the incoming data or information, and thatimage is stored for a period that is adequate to permit projecting ofthe image.

According to another aspect of the invention, an imager includes aliquid crystal member having an alterable optical function for affectingthe transmission, scattering or absorption of light incident thereon, asupport for supporting the liquid crystal member in sheet-like,strip-like (e.g. an endless loop or strip), disk-like, etc., lay out,the liquid crystal device being responsive to a prescribed input toalter such optical function and being operative to form characteristicsof an image, an input device for selectively applying the prescribedinput to respective portions of the liquid crystal member, and theliquid crystal member having a memory function for at least temporarilystoring the image characteristics after termination of a direct inputthereto by the input device.

Importantly, since the liquid crystal member has the characteristic ofbeing able to store image characteristics for a period of time, it ispossible to "write" images onto the liquid crystal member at a differentspeed than the image is carried into the projection optics, isprojected, and is removed from the projection optics. For example, usingrelative motion and/or other techniques, the speed with which the liquidcrystal member passes a "write" zone and the time in that zone to have aframe-like image written thereto may be different from the speed withwhich the frame is carried to the projection optics and the effectivetime in the projection optics. Consistently, the speed of erasing animage and the speed of writing also may be different.

According to a further aspect of the invention an apparatus formechanically depositing electric charge to a surface of a sheet-likeliquid crystal material having opposite surfaces, includes a dynamicelectrode having plural electrode means respectively electricallyisolated from each other for applying electrical surface charge withrespect to selected surface areas of such sheet-like liquid crystalmaterial, electrical means for applying an electrical voltage torespective electrode means, and movement means for effecting relativemovement of said dynamic electrode and such sheet-like liquid crystalmaterial.

In one embodiment of the invention the liquid crystal device of theimager includes encapsulted liquid crystal material formed as and/orsupported on a sheet, strip or disk. Such encapsulaed liquid crystalmaterial is capable of absorbing, scattering, and/or transmitting lightin response to a prescribed input, such as an electric field. Theencapsulated liquid crystal material has an electrical capacitancecharacteristic and, therefore, is capable of temporarily storing anelectrical charge applied thereto. Electrical charge selectively isapplied to designated areas of the encapsulated liquid crystal materialfor temporary storage there. Characteristics of an image, then, arecreated by the encapsulated liquid crystal material as a function of therespective areas thereof that are storing an electrical charge (and alsoas a function of the mangitude of such stored electrical charge and theelectric field produced thereby) and those areas of the liquid crystalmaterial where there is no electrical charge stored. A scanning oraddressing mechanism according to the invention facilitates thescanning, traversing or relative movement of the encapsulated liquidcrystal material selectively by a dynamic electrode or other means toapply such electrical charge thereto. The image characteristics formedby the encapsulated liquid crystal material may be projected. Moreover,after such image characteristics contained in a frame-like area of theliquid crystal member have been projected, that frame may be erased or,alternatively, permitted to have the image dissipate and, thus,effectively self-erase. Preferably the encapsulated liquid crystalmaterial is of the operationally nematic type, which has theadvantageous characteristics of prompt response to the application orremoval of an electric field, reversability, and the ability to scatter,to absorb, and/or to transmit light controllably in response to theapplication or removal of such prescribed input.

Another aspect of the invention relates to use in a projector, or thelike, particularly a motion picture type of projector, of a liquidcrystal member that has qualities permitting image characteristics to bewritten thereto, permitting the image characteristics to be storedthereby, and permitting the image characteristics to be erasedtherefrom.

An example of a liquid crystal member having such qualities is thecombination of a smectic liquid crystal material contained in volumesformed in a containment medium. The smectic liquid crystal material mayhave different ordinary and extraordinary indices of refraction with theordinary index of refraction being match to the index of refraction ofthe containment medium. Therefore, depending on whether the smecticliquid crystal material is in parallel alignment or in distortedalignment, the smectic liquid crystal member would function opticallygenerally in the manner summarized above.

Smectic liquid crystal material has a memory characteristic forstructural alignment thereof. Distorted alignment of the smectic liquidcrystal may be achieved by heating the liquid crystal material to atemperature above the isotropic temperature thereof. Thereafter, uponcooling of the liquid crystal material to a temperature below theisotropic temperature, the structure thereof will conform according toor otherwise be forced by the walls of the containment medium to thedistorted alignment configuration. Such liquid crystal structure willremain distorted until subjected to a further imput, such as an electricfield that is great enough to cause the liquid crystal structure toalign with respect thereto. Moreover, due to the memory characteristicof the smectic liquid crystal material, the parallel aligned structurethereof will remain even after removal of the electric field.

With the foregoing in mind, then, an embodiment of the invention using asmectic liquid crystsal member (or one or more sequential frames thereoftraveling through the projector of the invention) may be made fullyscattering by subjecting the same to adequate heat to raise thetemperature, say of a given frame thereof, above the isotropictemperature and then allow the liquid crystal material to cool to assumedistorted structural configuratin. Thereafter, selective application ofelectric field to areas of such frame will cause parallel alignment ofliquid crystal to reduce scattering at such respective areas. Suchapplication of electric field may be in a sense temporarily permanent,i.e. by temporarily storing the electric charge on the surface ofselected portions of the frame, as was described above; alternatively,such electric field may be applied by separate electrode members, etc.,between which the frame passes, since the aligned condition of liquidcrystal structure will remain after the temination of the electric fielduntil the heat to erase step is carried out again.

It is noted that the time during which the smectic liquid crystalmaterial memory functions to retain the parallel alignment within avolume of containment medium that is attempting to act on the liquidcrystal structure to distort it may vary according to the materialsused. However, it is desirable that such memory time be adequate topermit projecting the image before the image characteristics of a frameare lost or are so dissipated as to reduce substantially the quality ofthe projected image.

According to another embodiment of the invention using liquid crystalmaterial with a memory, such as smectic liquid crystal material,electric field may be used to erase one or more frames of the liquidcrystal member by aligning the liquid crystal material thereof inparallel with such field, thus making such frame(s) opticallytransparent. Thereafter, selectives application of thermal energy (heat)to prescribed areas of a frame or frames could be used to writeinformation to the frame. Such application of thermal energy would beadequate to raise the area where so applied to a temperature aboveisotropic temperature, as aforesaid, to cause the liquid crystalstructure there to enter isotropic phase; thereafter, upon cooling to atemperature below isotropic temperature such liquid crystal would be indistorted structural alignment to scatter light. A laser or other meansmay be used as the source of such thermal energy; the advantage of alaser is that conventional technology used to sweep a laser across asurface and to modulate the laser, e.g. as in laser printer devices, maybe used to achieve the desired application of thermal energy withrelatively high degree of precision and resolution of the created andprojected image.

Rather than heating the smectic liquid crystal material to a temperatureabove the isotropic temperature to cause the smectic liquid crystal toassume distorted alignment, it may be possible, depending on the natureof the smectic liquid crystal meterial, to heat the smectic liquidcrystal material to a temperature that is above the smectic nematictransition temperature. Above such transition temperature the liquidcrystal structure would behave as nematic or operationally nematicliquid crystal so as to lose the memory characteristic of smectic liquidcrystal material and, thus, to permit the liquid crystal structure to bedistorted to curvilinear alignment by the walls of the containmentmedium acting thereon. Accordingly, in the description herein, referenceto isotropic temperature of the liquid material is intended to mean notonly the actual isotropic temperature but also may mean the smecticnematic transition temperature if the latter in fact would function topermit achieving the distorted structural alignment as is described.

Some terms used herein generally are defined as follows: "liquid crystalmaterial" broadly refers to any type of liquid crystal material thatwill work in the context of the present invention, but preferably refersto nematic, smectic, opertionally nematic or operationally smecticliquid crystal material. Such liquid crystal material may includepleochroic dyes, non-pleochroic dyes, chiral compounds, or otherco-ingredients. A capsule refers to a containment device or medium thatcontains or confines a quantity of liquid crystal material, and"encapsulating medium" or "material" is that medium material of whichsuch capsules are formed. The capsules may be closed, e.g. as a closedsphere, having an interior volume containing liquid crystal material ormay be partially closed so as to define a specified volume forcontaining the liquid crystal material while one or more passageways orother means actually interconnect the interior volumes of two or moresuch capsules. An "encapsulated liquid crystal" or "encapsulated liquidcrystal material" means a quantity of liquid crystal material confinedor contained in the capsules of either or both types formed by and/or inthe encapsulating medium, for example in a solid medium as individualcapsules or dried stable emulsions.

Capsules according to this invention generally have an approximatelyspherical configuration (through this is not, per se, a requisite of theinvention) having a diameter from about 0.3 to 100 microns, preferably0.3 to 30 microns, especially 0.5 to 15 microns, for example mostpreferred 1 to 5 microns. In the context of this invention,encapsulation and like terms refer not only to the formation of sucharticles as are generally referred to as capsules, but also to theformation of stable emulsions or dispersions of the liquid crystalmaterial in an agent (an encapsulating medium) which results ininformation of stable, preferably approximately uniformly sized,particles in a uniform surrounding medium. Techniques for encapsulation,generally referred to as microencapsulation because of the capsule size,as well known in the art (see, e.g., "microcapsule Processing andTechnology" by Asaji Kondo, published by Marcel Dekker, Inc.) and itwill be possible for one skilled in the art, having regard to thedisclosure herein, to determine suitable encapsulating agents andmenthods for liquid crystal materials.

A feature of the spherical or otherwise curvilinear surfaced capsules orvolumes which generally confine the liquid crystal material therein inaccordance with the present invention is that the liquid crystalmaterial tends to be forced or distorted to a specific form, beingfolded back on itself in a sense as it follows and/or generally alignsparallel or normal to the capsule wall, so that the resulting opticalcharacteristic of a given capsule containing liquid crystal material issuch that substantially all light delivered thereto will be affected,for example, scattered (when no pleochroic dye is present) or absorbed(when pleochroic dye is present), or absorbed (when pleochroic dye ispresent), when no electric field is applied, regardless of thepolarization direction of the incident light. However, in response toapplication of an electric field to the encapsulated liquid crystalmaterial, the liquid crystal structure aligns with the field andscattering or absorption of light is reduced.

In the case of smectic liquid crystal material, the memorycharacteristic of the liquid crystal is operative to maintain theparallel structural alignment thereof after removal of electric fieldeven in the presence of the distorting forces applied by the containmentmedium walls. The duration of such memory may be very long or rathershort, depending on the nature of the liquid crystal material, themagnitude of the forces tending to distort the straight line structurethereof, and so on. As was mentioned above, resetting of the smecticliquid crystal structure may be accomplished by heating the smecticliquid crystal material to a temperature that exceeds the isotropictemperature thereof and then allowing the liquid crystal material tocool to a temperature below such isotropic temperature.

Exemplary operationally nematic encapsulated liquid crystal materialuseful in the present invention is disclosed in applicant's abovepatents and co-pending U.S. Patent applications. Exemplary operationallysmectic liquid crystal material useful in the invention includes:

Advantageous features inuring to the invention include improvedcontrast, coolness of operation, and versatility of the display andimage. Contrast is improved over prior art photographic and transparencyfilm displays, for example, because light is not absorbed by an emulsionor other absorbing material on the transparency; rather, in theinvention light is scattered and blocked, not being permitted to passthrough the aperture or is focused and blocked by a mask. Since lightintentionally preferably is not absorbed by the liquid crystal displayof the invention, heat energy does not have to be dissipated by thelight absorbing material; therefore, the overall operation of theprojector is cooler, a separate blower and/or heat filters could beeliminated, the potential of heat damage to the display is minimized,et. Versatility of the projector according to the invention resides, forexample, in the ability conventiently to change the phase of the image,for example, conventiently being able to project bright characters on adark background or vice versa as well as the ability conveniently tochange the image by changing the electrical input to the liquid crystaldisplay and, therefore, controlling which portions of the displayscatter and which portions transmit light. Also, filters color filtersconveniently can be added at the light output of the projector.

These and other embodiments of the invention will become apparent as thefollowing description proceeds.

To the accomplishment of the foregoing and related ends the invention,then, comprises the features hereinafter fully described andparticularly pointed out in the claims, the following description andthe annexed drawings setting forth in detail certain illustrativeembodiments of the invention, these being indicative, however, of but afew of the various ways in which the principles of the invention may beemployed.

BRIEF DESCRIPTION OF DRAWIGS

In the annexed drawings:

FIG. 1 is a schematic representation of a liquid crystal motion pictureprojector in accordance with the present invention;

FIG. 2 is a fragmentary schematic side elevation/perspective view of aliquid crystal imager in accordance with the present invention;

FIG. 2A is a fragmentary schematic view of a projector using a chargespraying device to apply charge to the liquid crystal film material;

FIG. 2B is a fragmentary schematic view of another projector using acathod beam stream of electrons to apply surface charge to the liquidcrystal film;

FIGS. 3 and 4 are enlarged schematic illustrations of a liquid crystalcapsule in accordance with the present invention respectively under ano-field condition and under an applied electric field condition;

FIG. 5 is a schematic illustration like FIGS. 3 and 4 showing analternate embodiment of encapsulated liquid crystal;

FIG. 6 is a plan view of the rolling dynamic electrode of the imager ofFIG. 2;

FIG. 7 is a schematic block diagram of the electronics portion of theimager of FIG. 2;

FIG. 8 is a fragmentary side elevation view of the sheet-like strip ofliquid crystal material of FIG. 2 with respective surface chargesapplied to the surface thereof;

FIG. 9 is a schematic illustration of a liquid crystal projector inaccordance with the present invention;

FIGS. 10 and 11 are fragmentary schematic illustrations of alternatelight output mechanisms used in connection with the projection lens inthe projector of FIG. 9;

FIGS. 12A and 12B are, respectively, a schematic representation of lightscattered by the liquid crystal display of FIG. 10 and a graph ofintensity of projected light as a function of electrical inputmagnitude;

FIG. 13 is a schematic illustration of a folded liquid crystal projectorin accordance with the prefered embodiment and best mode of theinvention with a dynamic color filter;

FIG. 14 is a plan view of the dynamic color filter;

FIG. 15 is a dyed display for use in the projectors; and

FIG.16 is a projector for use with smectic liquid crystal in whichcharge or electric field is used to write an image and heat is used toerase an image from the "film";

FIG. 17 is another projector similar to that of FIG. 16 for use withsmectic liquid crystal in which the heat is used to write an image andcharge or electric field is used to erase the image from the "film";

FIG. 18 is a schematic view of a projector that uses a liquid crystalimage storage medium in the form of a disk on which charge may be storedto retain the image;

FIGS. 19 and 20 are schematic views of projectors similar to those FIGS.16 and 17, but here using a disk type smectic liquid crystal storagemedium; and

FIG. 21 is a schematic view of a further smectic liquid crystalprojector that uses a pair of electrodes detached from the liquidcrystal storage medium for applying electric field selectively to alignthe structure of selected liquid crystal.

DETAILED DESCRIPTION

Referring, now in detail to the drawings, wherein line referencenumerals disignate like parts in the several figures, and initially toFIG. 1, a liquid crystal motion picture projector in accordance with theinvention is designated 1. The projector 1 includes a liquid crystalimager or display device 2 and projection optics 3 for projecting imagessequentially created by the imager 2. The imager 2, sometimes referredto as a liquid crystal display, includes a "film" in the form of acontinuous strip 4 of liquid crystal material capable of temporarilystoring charge to create characteristics of an image on a frame by framebasis that can be projected and a charge applicator 5 selectively toapply charge to the liquid crystal material to create the sequentialimages. The projection optics 3 includes a projection lens 6 and variousother optics, such as light source, mask, shutter and lens systemsgenerally designated 7 capable of projecting the sequential imagescreated by the imager 2 onto a screen 8. A housing or case 9 may beprovided to contain the parts 2-7 of the projector. If desired, thehousing 9 may be light tight to prevent undesirable escape of lightgenerated by the projection optics 3.

Details of the projection optics 3 will be described further below, forexample with reference to FIGS. 9-15. Suffice it to say here that it isthe function of the imager 2 to create plural frames of images orepresentations of images by liquid crystal that scatters light ortramsmits light without scattering it; and it is those images that areprojected. Moreover, the imager 2 is capable of continuously supplyingsequential images to the projection optics wihout the need for a largereels of film or the like. Those sequential images are created atsequential locations on the continuous strip 4, are projected, andsubsequently are replaced. After projection of an image and beforereplacement by another image, an image may be erased or allowed todissipate.

The continuous strip 4 is formed of liquid crystal material that has acapacitance characteristic which enables charge to be stored on thesurface 4S thereof. The surface charge together with an electrode, whichis formed as part of the strip 4 and perferably is at a referencepotential, such as ground, creates an electric field at a selected areaof the strip between such charge and electrode. Temporary storage ofsuch charge to provide electric field functions as a memory to retainthe image characteristics of a frame until after it has been projected.Details of the imager 2, including of the strip 4 and of the chargeapplicator 5, will be described in further detail below.

The charge applicatior 5 applies such charge preferably just prior tothe projection optics 3 to minimize dissipation between the time thecharge is applied and the time the image is projected. A metal roller 10rolls against the strip 4 or at least part of it to make contact withthe mentioned electrode to maintain the same at ground referencepotential, as is seen at the connection 11 to a relatives ground, forexample. Such electrode perferably is continuous over the entire lengthand width of the strip and, therefore, is maintained at ground by suchconnection. Means other than the roller 10 may be used for such groundor other reference potential connection.

Additionally, the imager 2 includes plural rollers 12 along which thestrip is moved during cyclical movement along a continuous path, as isseen in FIG. 1. A motor 13, such as a synchronous motor, may be used todrive one or one pair of the rollers 12', e.g. a sprocket type drive, todrive the continuous strip along its path designated by directionalarrows 14. Preferably there are two pairs of drive sprockets 12' locatedin conventional manner with respect to the strip 4, and the motor 13 iscoupled by a shaft 13' to turn such drive sprockets. Loops 4a may beprovided in the film 4 as in a conventional motion picture projector toallow for a time delay of each frame to be retained in position in theprojection optic 3 while the rest of the film 4 moves at a generallyconstant speed.

The charge applicator 5 is operative at a charge applying station 15upstream of the projection optic 3. Therefore, promptly after the chargeapplicator 5 applies a charge to the strip to create an image in a givenframe, such frame passes to alignment with the projection optics and theimage therein is projected. There is no restriction of where on thelength of the strip 4 an image forming a given frame is formed; however,there should be synchronization of the charge applicator 5, the movementof the strip 4 and the operation of the projection optic 3, such as theshutter, etc. thereof, to assure projection of a quality image.

Top and bottom (or input and output), loops 4' in the liquid crystalstrip 4 may be provided using several pairs of rollers 12 and/orsprockets 12' in the usual fashion employed in conventional motionpicture projectors. Such loops 4' in a particular permit individualframes to remain in fixed position in the optical path of the projectionoptic 3 for a prescribed period of time for projection while the strip 4outside such projection optics area is driven by the motor at asubstantially constant speed.

Discharge rollers 16, 17 discharge any remaining charge on strip 4 priorto reapplication of charge by the charge application 5. Such dischargerollers 16, 17 preferably are electrically conductive material thatcouple to the surface 4S and to the strip electrode (not shown inFIG. 1) to assure discharging. The discharge rollers 16, 17 preferablyare connected to ground 11 or are otherwise connected to achieve thedischarge function. The discharge rollers 16, 17 may have smoothcylindrical surfaces for good engagement with the surface 4S and theelectode 27; may be flat or stepped wiping surfaces either stationary ormovable, e.g. a stepped surface would wipe an exposed edge of electrode27; may be series of wire-like projections that wipe across the strip 4;etc., to achieve the desired discharging function.

In the event that the charge on a given area, e.g. that forming a givenframe, of the strip generally adequately dissipates before that area isre-presented to the charge applicator 5 for appropriate recharging, orif separate discharging is unnecessary prior to recharging by the chargeapplicator 5, the discharge rollers 16, 17 may be unneeded.Alternatively or additionally, the idler rollers 12 and/or drivesprockets 12' downstream of the projection optics may be electricallyconductive and connected to ground to effect discharging function.Advantageously, the sprocket, for example, has teeth that pass throughthe strip and can be electrically conductive to form a good connectionwith the electrode 27 coupling the same to ground. The rollers 12 anddrive sprocket 12' upstream of the projection optics 3 and between theprojection optics and the charge applicator 5 may be electricallynon-conductive so they do not discharge or dissipate stored charge.

The charge applicator 5 preferably is in the form of a dynamicelectrode, as is described in detail below with reference to FIGS. 6-8.Moreover, associated with the charge applicator 5, and, if desired,considered a part of the imager 2 along hte strip 4, charge applicator 5and various rollers and associated parts, is a computer/programmed drive18. The drive 18 has as its function the control of the chargeapplicator 5 to determine at what areas of the strip charge is to beapplied and at what areas charge is not to be applied. Moreover, thedrive 18 may include means to determine the magnitude of such charge sothat in a sense a gray scale function can be accomplished in the imageprojected onto the screen 8. Thus, in the computer/programmed drive 18may be a memory, such as RAM, ROM, disk, tape, or other volatile ornon-volatile memory, capable of storing information indicating when andwhere charge is to be applied or not to the strip to create a series ofsequential image frames that can be projected to create a movingpicture, for example. Alternatively, the computer/programmed drive 18may include circuitry for detecting and/or decoding incoming informationfrom another source, such as a local or remote computer, e.g. via amodem connection, to effect control of the charge applicator 5 to createthe desired images on the strip 4.

In view of the foregoing briedf description and the following detaileddescription, it will be appreciated, then, the information to createsequential image frames on the strip 4 for proj663ion by the projectionoptics 3 can be stored in as solid state or other electronic memorylocally, i.e. at or in proximity to the projector 1, or may be receivedfrom a distant source.

Turning preliminarily to FIG. 2, the imager 2 preferably is capable offorming an image representing the information received from the drive 18an applicator 5 essentially in real time, i.e. essentially at the sametime that the informtion is received from the drive 18 without requiringany slow-down of the rate at which the input information is received.Additionally, the imager 2 is capable of storing or maintaining suchimage for a period adequate to permit projecting thereof by theprojection optics 3 e.g. as a function of surface charge storage on thesurface 4S of the strip 4. Furthermore, the liquid crystal strip 4,indeed the entire projector 1, preferably is capable of substantiallycontinuous use to form one image after another and to project each ofthe images to create a moving or like image on the screen 8. Thelimitations on speed of operation of the liquid crystal projector 1 maybe, for example, the rate at which information can be received as theapplicator 5, the rate at which such input informtion can be convertedto an image, which may be effected essentially simultaneously uponreceipt of the information, and the operational speed of the strip 4 andprojection optics 3. It is possible to apply the image characteristicsto the strip 4 at a speed different than the speed the strip 4 travelsthrough the projection optics 3, as is described further below.

The imager 2 converts input informatin received from the drive 18 anapplicator 5 to an image on the strip 4 capable of being projected. Thestrip 4 includes an encapsulated liquid crystal layer 25 mounted forsupport on a sheet-like support 26, for example of Mylar or similarrelatively strong optically transparent material. An opticallytransparent electrode 27 covers the surface 28 of the support 26 andseparates the latter from the liquid crystal layer 25. The chargeapplicator 5, in response to the information received from the driver18, applies a prescribed input, in the preferred embodiment a chargethat produces an electric field, to selected areas on the surface 4S ofthe encapsulated liquid crystal layer 25 thereby to form an imagerepresented by the information received.

The encapsulated liquid crystal layer 25 is encapsulated liquid crystalmaterial 30 formed of a containment medium or encapsulating medium 31and liquid crystal material 32. Exemplary materials for the containmentmedium 31 include, for example, polymers, for example polyvinyl alcohol(PVA), gelatin, latex and various other material, for example which arementioned in the aforementioned patent applications. Epoxy is anotherexample of a containment medium. The liquid crystal material 32preferably is nematic or operationally nematic and, for example, may beof one or more of the liquid crystal materials disclosed in theaforementioned patent applications. Alternatively the liquid crystalmaterial 32 may be smectic or operationally smectic, as is described infurther detail below. The containment medium 31 and liquid crystalmaterial 32 cooperate to form a plurality of capsules, volumes,containment areas, or the like generally represented at 33, each ofwhich may be closed or partly closed, in the latter case two or more ofthe so-called capsules may be fluidically coupled by interconnectingpassageways like in a matrix formed of the medium and liquid crystal.The interior wall of a capsule generally tends to distort the structureof the liquid crystal material therein causing the same to assume adistorted or generally curivinearly aligned structure, as opposed to theusual straight line parallel structure that nematic liquid crystalmaterial tends to assume in the absence of a prescribed input,hereinafter referred to as an electric field, which is the preferredprescribed input in accordance with the invention. Such distortedstructure typically would be aligned generally either parallel or normalto the capsule wall. However, in the presence of such electric field,the structure of the liquid crystal material 32 in the capsules 33 tendsto align with respect to the field. On removal of the field again,though, the capsule wall effects the aforementioned distorted alignment.A plurality of capsules 33 preferably several capsules thick preferablymake up the encapsulated liquid crystal layer 25 generally as isrepresented in the illustration of FIG. 2. The overall thickness of suchlayer 25 may be, for example, from about 0.3 mil to about 10 mils (about0.5 mil being preferred), and the approximate diameter of each capsulemay be, for example, from about 0.3 micron to about 100 microns, or oneof the ranges above, with about 1 micron to about 5 microns beingpreferred. The capsules may be arranged in discrete layers or, morepreferably, in a generally random, but nevertheless relatively closepacked relation generally as is shown in the illustration of FIG. 2.

The shape of the interior surfaces of the volumes containing the liquidcrystal material also should tend to distort the liquid crystal materialwhen in a field-off or random alignment condition. A particularadvantage to the preferred spherical configuration of the volumes is thedistortion it effects on the liquid crystal therein when in a field-offcondition. This distortion is due, at least in part, to the relativesizes of the volumes and the pitch of the liquid crystal; theypreferably are about the same or at least about the same order ofmagnitude. Moreover, nematic liquid crystal material has fluid-likeproperties that facilitate the conformance or the distortion thereof tothe shape of the capsule or volume wall surfaces in the absence of anelectric field. On the other hand, in the presence of an electric fieldsuch nematic material will relatively easily change to ordered alignmentwith respect to such field.

The liquid crystal material 32 is optically anisotropic having ordinaryand extraordinary indices of refraction; and the containment medium 31preferably is substantially optically transparent, for example from theultraviolet to the far infrared wavelength range. The index ofrefraction of the containment medium 31 and the ordinary index ofrefraction of the liquid crystal material 32, i.e. the index ofrefraction parallel to the optical axis of the liquid crystal (andoccurring in the presence of an electric field which aligns the liquidcrystal, as aforesaid) are optically matched so that in the presence ofan electric field light may be transmitted substantially directlythrough the layer 25 without or at least with only a minimum ofrefraction at interfaces between liquid crystal material 32 andcontainment medium 31. However, the extraordinary index of refraction ofthe liquid crystal material should be different from the index ofrefraction of the containment medium thereby to increase the refractingand scattering of light in the encapsulated liquid crystal layer 5 inthe absence of an electric field.

The electrical characteristics of the containment medium 31 and theliquid crystal material 32 are such that preferably in response to theapplication of a voltage thereto the major electric field producedthereby will be across the liquid crystal material and minimum voltagedrop will occur across the encapsulating medium itself. Accordingly, thecontainment medium 31 should have a dielectric constant no less than thelower dielectric constant of the liquid crystal material, which iselectrically anisotropic, and a relatively large impedance. Ideally, thedielectric constant of the encapsulating medium 31 should be close tothe higher dielectric constant of the liquid crystal material, too.

Viewed on a so-called macroscopic or collective level, the encapsulatedliquid crystal layer 25 essentially is a dielectric material having anaverage dielectric constant value, which may vary slightly during use,e.g. according to application or removal of an electric field to theliquid crystal material 32, and which also may be a function of theoverall materials of which the layer 25 is composed. Accordingly, theencapsulated liquid crystal layer 25 has the ability to function as acapacitor storing an electric charge, namely a voltage, which may beapplied thereacross. As is described further below, then, it is thefunction of the charge applicator 5 to apply surface charge to selectedareas of the layer 25 for temporary storage and to create the imagecharacteristics in the liquid crystal material for copying.

The usual free form structure of nematic liquid crystal and of smecticliquid crystal is parallel alignment. In nematic liquid crystal suchparallel alignment generally is not further constrained. However, insmectic liquid crystal there is a further alignment constraing, wherebythe parallel aligned liquid crystal also is organized in layers, whichis what causes the so-called bulk effect structural storagecharacteristic of smectic liquid crystal. Both nematic and smecticliquid crystal materials used in the invention may be operative toassume a distorted alignment to scatter light and/or to effect lightabsorption, particularly if pleochroic dye is present, and may beoperative to assume a parallel alignment in response to an electric (ormagnetic) field to reduce such scattering or absorption. The nature ofand mechanism to achieve such alignment is described below with respectto nematic or operationally nematic liquid crystal. The mechanism toeffect such alignment of smectic liquid crystal is described furtherbelow.

Turning to FIGS. 3 and 4, a schematic representation of a single capsule33 containing liquid crystal 32 is shown, respectively, in the field-offand field-on conditions. The capsules 33 are spherical and have agenerally smooth curved interior wall surface 34 defining the boundaryfor the interior volume or volumetric space 35 thereof. The actualdimensional parameters of the wall surface 34 and of the overall capsule33 are related to the quantity of liquid crystal 32 contained thereinand possibly to other characteristics of the individual liquid crystalmaterial therein. Additionally, the capsule 33 applies a force to theliquid crystals 32 tending to pressurize or at least to maintainsubstantially constant the pressure within the volume 35. As a resultand as is shown in FIG. 3, the liquid crystals which ordinarily in freeform would tend to be parallel, although perhaps randomly distributed,are distorted to curve in a direction that generally is parallel to arelatively proximate portion of the interior wall surface 34. Forsimplicity of illustration, a layer 36 of liquid crystal molecules whosedirectional orientation is represented by respective dashed lines 37 isshown in closest proximity to the interior wall surface 34. Thedirectional orientation of the liquid crystal molecules 37, moreaccurately the liquid crystal structure, is distorted to curve in thedirection that is parallel to a proximate area of the wall surface 34.The directional pattern of the liquid crystal molecules away from theboundary layer 37 within the capsule is represented by 38. The liquidcrystal molecules are directionally represented in layers, but it willbe appreciated that the molecules themselves are not confined to suchlayers. Thus, the organization in an individual capsule is predeterminedby the organization of the structure 37 at the wall and is fixed unlessacted on by outside forces, e.g. an electric field. As is shown in FIG.4, upon application of electric field E across encapsulated liquidcrystal 30, the liquid crystal aligns with respect to the field.Preferably the liquid crystal 32 has positive dielectric anisotropy sothat such alignment is in parallel with such field to achieve theoptical results of reduced scattering since the ordinary index ofrefraction of the liquid crystal then is encountered by incident lightand preferably is matched to the index of refraction of the capsule 33.On removal of the electric field the directional orientation of liquidcrystal structure would revert back to the original one, such as thatshown in FIG. 3.

Nematic type material usually assumes a parallel configuration andusually is optical polarization direction sensitive. However, since thematerial 32 in the encapsulated liquid crystal 30 is distorted or forcedto curved form in the full three dimensions of the capsule 33, suchnematic liquid crystal material in such capsule takes on an improvedcharacteristic of being insensitive to the direction of opticalpolarization of incident light. The inventor has discovered, moreover,that when the liquid crystal material 32 in the capsule 33 haspleochroic dye dissolved therein, such dye, which ordinarily also wouldbe expected to have optical polarization sensitivity, no longer ispolarization sensitive because the dye tends to follow the same kind ofcurvature orientation or distortion as that of the individual liquidcrystal molecules.

Although the foregoing discussion has been in terms of a homogeneousorientation of the liquid crystal material (parallel to the capsulewall), such is not a requisite of the invention. All that is required isthat the interaction between the wall and the liquid crystal produce anorientation in the liquid crystal near that wall that is generallyuniform and piecewise continuous, so that the spatial averageorientation of the liquid crystal material over the capsule volume isstrongly curved and there is no substantial parallel direction oforientation of the liquid crystal structure in the absence of anelectric field. It is this strongly curved orientation that results inthe scattering and polarization insensitivity in the field-offcondition, which is a feature of this invention.

In the field-on condition, or any other condition which results in theliquid crystal being in ordered or parallel alignment, as is shown inFIG. 4, the encapsulated liquid crystal 30 will transmit substantiallyall the light incident thereon and will tend not to be visible in thecontainment medium or support medium. On the other hand, in thefield-off condition when the liquid crystal is in distorted alignment,sometimes referred to herein as random alignment, for example as isshown in FIG. 3, some of the incident light will be absorbed, but alsosome of the incident light will tend to be scattered generallyisotropically in the containment support medium 31. Using total internalreflection such isotropically scattered light can be redirected to theencapsulated liquid crystal 30 thus brightening the same tending tocause it to appear white to a viewer or viewing instrument.

As long as the ordinary index of refraction of the liquid crystalmaterial is closer to the index of refraction of the so-calledencapsulating or containment medium, than is the extraordinary index ofrefraction, a change in scattering will result when going from field-onto field-off conditions, and vice-versa. Maximum contrast results whenthe ordinary index of refraction matches the index of refraction of themedium. The closeness of the index matching will be dependent on thedesired degree of contrast and transparency in the device, but theordinary index of refraction of the crystal and the index of the mediumwill preferably differ by no more than 0.03, more preferably 0.01,especially 0.001. The tolerated difference will depend upon capsulesize.

The capsule 33 may be of various sizes. The smaller the size, though,the higher the requirements will be for the electric field to effectalignment of the liquid crystal in the capsule. Preferably, though, thecapsules should be of uniform size parameters so that the optical andelectrical characteristics of the encapsulated liquid crystal will besubstantially uniform. Moreover, the capsules 33 preferably are at least1 micron in diameter so they appear as discrete capsules relative to anincident light beam; a smaller diameter may result in the light beam"seeing" the capsules as a continuous homogenous layer and would notundergo the required isotropic scattering. Examples of capsule sizes,0.3 to 100 microns or say from 1-30 microns diameter, and of liquidcrystal material are in the above patents and application and are herebyspecifically incorporated by reference.

One preferred liquid crystal material in accordance with the best modeof the invention is that nematic material NM-8250, an ester that hasbeen sold by American Liquid Xtal Chemical Corp., Kent, Ohio, U.S.A.Other examples may be ester combinations, biphenyl and/or biphenylcombinations, and the like.

Several other types of liquid crystal material useful according to theinvention include the following four examples, each being a recipe forthe respective liquid crystal materials. The so-called 10% material hasabout 10% 4-cyano substituted materials; the 20% material has about 20%4-cyano substituted materials, and so on.

    ______________________________________                                        10% Material                                                                  Pentylphenylmethoxy Benzoate                                                                        54       grams                                          Pentylphenylpentyloxy Benzoate                                                                      36       grams                                          Cyanophenylpentyl Benzoate                                                                          2.6      grams                                          Cyanophenylheptyl Benzoate                                                                          3.9      grams                                          Cyanophenylpentyloxy Benzoate                                                                       1.2      grams                                          Cyanophenylheptyloxy Benzoate                                                                       1.1      grams                                          Cyanophenyloctyloxy Benzoate                                                                        9.94     grams                                          Cyanophenylmethoxy Benzoate                                                                         0.35     grams                                          20% Material                                                                  Pentylphenylmethoxy Benzoate                                                                        48       grams                                          Pentylphenylpentyloxy Benzoate                                                                      32       grams                                          Cyanophenylpentyl Benzoate                                                                          5.17     grams                                          Cyanophenylheptyl Benzoate                                                                          7.75     grams                                          Cyanophenylpentyloxy Benzoate                                                                       2.35     grams                                          Cyanophenylheptyloxy Benzoate                                                                       2.12     grams                                          Cyanophenyloctyloxy Benzoate                                                                        1.88     grams                                          Cyanophenylmethoxy Benzoate                                                                         0.705    grams                                          40% Material                                                                  Pentylphenylmethoxy Benzoate                                                                        36       grams                                          Pentylphenylpentyloxy Benzoate                                                                      24       grams                                          Cyanophenylpentyl Benzoate                                                                          10.35    grams                                          Cyanophenylheptyl Benzoate                                                                          15.52    grams                                          Cyanophenylpentyloxy Benzoate                                                                       4.7      grams                                          Cyanophenylheptloxy Benzoate                                                                        4.23     grams                                          Cyanophenyloctyloxy Benzoate                                                                        3.76     grams                                          Cyanophenylmethoxy Benzoate                                                                         1.41     grams                                          40% MOD                                                                       Pentylphenylmethoxy Benzoate                                                                        36       grams                                          Pentylphenylpentyloxy Benzoate                                                                      24       grams                                          Cyanophenylpentyl Benzoate                                                                          16       grams                                          Cyanophenylheptyl Benzoate                                                                          24       grams                                          ______________________________________                                    

The encapsulating or containment medium forming respective capsules 33should be of a type that is substantially completely unaffected by anddoes not affect the liquid crystal material. Various resins and/orpolymers may be used as the encapsulating medium. A preferredencapsulating medium is polyvinyl alcohol (PVA), which has a good,relatively high, dielectric constant and an index of refraction that isrelatively closely matched to that of the preferred liquid crystalmaterial. An example of preferred PVA is an about 84% hydrolized,molecular weight of at least about 1,000, resin. Use of a PVA ofMonsanto Company identified as Gelvatol 20/30 represents the best modeof the invention. Other containment media are latex and epoxy. Examplesof several containment media include carboxy polymethylene (e.g.Carbopole), various Gelvatol materials, Elvanol, and Poval.

A method for making emulsified or encapsulated liquid crystals 11 mayinclude mixing together the containment or encapsulating medium, theliquid crystal material, and perhaps a carrier medium, such as water.Mixing may occur in a variety of mixer devices, such as a blender, acolloid mill, which is most preferred, or the like. What occurs duringsuch mixing is the formation of an emulsion of the ingredients, whichsubsequently can be dried eliminating the carrier medium, such as water,and satisfactorily curing the encapsulating medium, such as the PVA.Although the capsule 33 of each thusly made encapsulated liquid crystal30 may not be a perfect sphere, each capsule will be substantiallyspherical in configuration because a sphere is the lowest free energystate of the individual droplets, globules or capsules of the emulsion,both when originally formed and after drying and/or curing.

In accordance with the invention, other various types of support media26 that may be used include Mylar, polyester materials and polycarbonatematerial, such as Kodel film. Tedlar film, which is very inert, also maybe used if adequate adhesion of the electrode can be accomplished. Suchmedia 26 preferably should be substantially optically transparent andshould have an index of refraction the same as or closely matched to theindex of refraction of the containment medium 31 so as not to contributeto further scattering or refracting of light.

Briefly referring to FIG. 5, there is shown an alternate embodiment ofencapsulated liquid crystal material 30', which may be substituted forthe various other embodiments of the invention disclosed herein. Theencapsulated liquid crystal material 30' includes operationally nematicliquid crystal material 32' in a containment medium 31', e.g. in theform of a spherical capsule. In FIG. 5 the material 30' is in field-offcondition, and in that condition the liquid crystal structure isoriented to be normal or substantially normal to the capsule wall at theinterface therewith. Thus, at the interface the liquid crystal structureis generally oriented in a radial direction with respect to the geometryof the capsule or in any event less parallel to the capsule wall thanthe embodiment of FIG. 3. Moving closer toward the center of thecapsule, the orientation of the structure of at least some of the liquidcrystal molecules will tend to curve in order to utilize, i.e. to fill,the volume of the capsule with a substantially minimum free energyarrangement of the liquid crystal in the capsule, for example, as isseen in the drawing.

Such alignment is believed to occur due to the addition of an additiveto the liquid crystal material 32' which reacts with the containmentmedium to form normally oriented steryl or alkyl groups at the innercapsule wall. More particularly, such additive may be a chrome sterylcomplex or Werner complex that reacts with PVA of the containment mediumthat forms the capsule wall to form a relatively rigid crust or wallwith a steryl group or moeity tending to protrude radially into theliquid crystal material itself. Such protrusion tends to effect thenoted radial or normal alignment of the liquid crystal structure.Moreover, such alignment of the liquid crystal material still complieswith the above strongly curved distortion of the liquid crystalstructure in field-off condition because the directional derivativestaken at right angles to the general molecular direction are nonzero.

The projector 1 of the invention preferably uses light that istransmitted through the liquid crystal material without refraction orthat is forward scattered by the liquid crystal material.

Referring to FIGS. 2, 6, 7 and 8, in response to selective applicationof a charge creating a voltage or electric field at certain areas of theencapsulated liquid crystal layer 25, for example at areas 25A and 25Brepresented on the surface 4S and the non-application of electric fieldto other selected areas of the layer 25, for example at areas 25C and25D represented on the surface 4S, alignment or not of that liquidcrystal which is directly between such respective area on surface 4S andthe electrode 27, or non-alignment (when no field is applied at a givenarea) can be achieved. Due to the effective capacitance of theencapsulated liquid crystal layer 25, when a charge is applied to aselected area, say at 25A, 25B, etc., such charge is stored and takes afinite time, for example several seconds or longer, to dissipate. Forthe duration of such stored charge, the electric field produced acrossthe selected encapsulated liquid crystal material generally locatedbetween such area and the electrode 20 will cause the desired parallelalignment of the liquid crystal structure with respect to such field.Accordingly, by selecting particular areas of the encapsulated liquidcrystal layer 25 at which electric field is to be applied, arepresentation of an image can be formed and stored by the encapsulatedliquid crystal layer 25.

To complete the effective formation of an image by the imager 2 inresponse to such selective application of charge to various areasthereof, illumination is required. According to the preferred embodimentand best mode of the invention the source of illumination is provided bythe projection optics 3. Such light source may illuminate the entireencapsulated liquid crystal layer 25 simultaneously for projection, asis described further below.

Effective formation of a viewable image capable of projection, forexample, preferably is carried out in accordance with the disclosure inthe above mentioned U.S. Pat. No. 4,606,611. At least a portion of thelight scattered by such liquid crystal material also will scatter in aforward direction, e.g. toward the projector lens 6 and associatedoptics described further below. On the other hand, light, for examplefrom the light source, which impinges onto that encapsulated liquidcrystal material 30 in the layer 25 which is aligned with respect to anelectric field will tend not to be scattered and, rather, will tend topass directly through such liquid crystal material and the layer 25 alsotoward the lens 6 and associated optics. It will be appreciated that byselecting those areas, e.g. 25A-25D, and so on, where surface charge isor is not to be applied to the surface 4S in order to apply an electricfield to selected encapsulated liquid crystal material in the layer 25,alphanumeric, graphical, pictorial, etc., images can be created, andthose images can be projected.

The charge applicator 5 applies charge to the film 4 or otherwise causesparallel alignment of selected liquid crystal structure in the film. Inthe embodiment illustrated in FIGS. 2, 6 and 7, the charge applicator 5includes, for example, an electronics portion 40, a drive motor 41 and adynamic electrode 42. Responding to the information received from thecomputer/programmed drive 18 or other input system, the chargeapplicator 5 decodes such information and based thereon applies surfacecharge to selected areas of the surface 23 of the encapsulated liquidcrystal layer 25. The drive motor 41 operates in response to controlsignals and/or power from the electronics portion 40 (possibly power maybe provided from an external source, not shown). The dynamic electrode42 is shown as a generally cylindrical scanning roller 43, which is seenin front elevation view in FIG. 6. Scanning here refers to relativemovement occurring between the dynamic electrode 42 and the surface 4Sto enable various locations on such surface in a sense to be addressedand to receive surface charge. Preferably the roller 43 is ofelectrically non-conductive material, and the roller has thereon aplurality of electrically conductive electrode strips 44. The electrodestrips 44 are formed on or attached to the non-conductive exteriorsurface 45 of the roller and are electrically isolated from each other.The electrode strips 44 extend in annular fashion preferably completelycircumferentially about the roller 43. The electrode strips 44respectively are positioned in planes that are perpendicular to the axis46 of the roller 43 so that as the roller rolls along the surface 4Spreferably in a direction perpendicular to the roller axis and withoutslippage on the encapsulated liquid crystal layer 5, each rotatingelectrode strip 44 follows a straight line path along such surface 4S.

The roller 43 may be mounted so the axis thereof does not in fact move.Rather, the surfaces of the electrode strips roll along the surface 4Sof the strip 4 as the latter is moved along its own continuous path bythe motor 13 and drive roller 12. If desired the motors 13, 41 may be asingle motor with appropriate drive connections to the roller 12 andelectrode 42.

The electronics portion 40 cooperates with, monitors, and controls themotor 41, the position of the dynamic electrode 42 along the surface 4S,and the voltage applied (or not applied) to respective electrode strips44. The electronics portion 40 also is connected to the electrode 27,which preferably is over the entire lower surface 4L of the encapsulatedliquid crystal layer 25, e.g. using roller 17, and the potential of suchelectrode 27 is maintained, for example, at a relative ground potentialso that voltage applied to an area of the surface 4S by an electrodestrip 44 would be with respect to such ground or other referencepotential. Appropriate wipers, brushes or other means may be used toconnect the electrode 27 to the electronics 40 and/or to the rollers 15,17.

In the electronics portion 40 the information from the input system 18,for example in the form of a serial input represented at 50, isconverted to parallel information by a conventional serial to paralleldecoder 51. The serial to parallel decoder 51 may be a conventionalserial to parallel decoder, such as an integrated circuit device, forexample a UART (universal asynchronous receive transmit device), or aplurality of the same, which produce parallel information on theparallel output lines 52 directly representative of the serial inputinformation. Such parallel output lines 52 are respectively connected tothe individual electrode strips 44 to apply any voltage on therespective output line to a respective electrode strip. If necessaryvarious conventional logic circuitry may be used to decode the inputdata from the input system 18 to derive the parallel output data as theroller 43 rolls along the surface 4S. Accordingly, the respectiveelectrode strips 44 apply such voltage(s) to the particular area(s) ofthe encapsulated liquid crystal layer 25 surface 4S with which suchelectrode strips 44 at that moment are engaged. Moreover, as the dynamicelectrode 42 rolls along the surface 4S, such rolling movement ismonitored and controlled by a synchronizing portion 53 of theelectronics portion 50 e.g. relative to movement of the strip 4.

The synchronizing portion 53 in response to information from the serialinput 50 synchronizes rolling movement of the dynamic electrode 42 andthe signals produced on the serial to parallel decoder 51. In operationof the charge applicator 5, then, information, for example in the formof serial data, is received from the input system 18. That data isconverted by the decoder 51 to parallel data supplied on the outputlines 52 to respective electrode strip 44 when the dynamic electrode 42is at a particular location on the surface 4S of the encapsulated liquidcrystal layer 25; the foregoing is controlled according to thesynchronization circuit 53 which operates the motor 41 that moves thedynamic electrode 42 and also preferably monitoring position of thedynamic electrode 42 relative to the strip 4. The synchronizationcircuit 53 continues to allow the motor 41 to move the dynamic electrode42 along the surface 4S as additional information is received from theinput system and the circuit 53 also continues to allow the decoder 51to decode the new information and to provide appropriate alterations inthe signals on the output line 52 which if necessary appropriately alterthe voltage applied to respective electrode strips 44 depending on thenature of the input information. As the dynamic electrode 42 rolls alongthe surface 4S, then, the electrode strips 44 apply surface charge toselected areas, such as areas 25A, 25B. Such surface charge results inthe application of an electric field between the respective area and theelectrode 27 at the opposite surface 4L of the encapsulated liquidcrystal layer 25 causing parallel alignment of the encapsulated liquidcrystal material 30 therebetween. As was mentioned above, theencapsulated liquid crystal layer 25 has dielectric and resistivecharacteristics so as to be capable of storing such surface charges atthe respective areas for a period of time that is adequate for theprojection optics 3 to project the image effectively created in theencapsulated liquid crystal layer 25.

As is shown in FIG. 8, different surface charges can be applied todifferent surface areas of the surface 4S. For example, at areas 25A and25B a positive charge has been deposited, and at areas 25C and 25D thereis no charge. The deposited charge may be positive or negative. Forexample, at areas 25A' and 25B' negative charge is shown. Also, ifdesired, to expedite discharging an area of a given polarity, a chargeof opposite polarity or a ground discharging connection made via therespective electrode strip passing over the respective area may beemployed.

It will be appreciated that means other than the dynamic electrode 42may be used to applycharge to the film 4. For example, other types ofdynamic electrodes that are not cylinders with continuous electrodebands 43 may be used.

Also, as is illustrated in FIG. 2A, an electric charge spraying deviceor source 42a may be used to spray charge 43a toward the surface 4S offilm 4. Such charge spraying devices are conventional and may be usedunder control of the electronics 40 to determine where to spray charge43a (and where not to spray charge). A motive mechanism 41a (such as amotor and a rotating support) may be used to move the device 42a to scanor to sweep the same and any sprayed charge across the surface of film 4passing relative thereto, or plural spray devices 42a may be used tospray charge at respective location on the film 4, in either case theobjective being accomplished to spray charge onto selected areas at anylocation on the entire surface of the film 4.

As another example, in FIG. 2B is shown a beam of electrons directedtoward and swept across the surface of film 4 to applysurface charge.Such electron beam may be generated by a cathode ray tube type device orthe like indicated at 42b, while the film moves along its path 14. Thus,image characteristics for respective frames may be created byselectively applying charge to selected locations on the film 4 to causeparallel alignment of liquid crystal at such locations and not applyingcharge to other locations.

The Projector Apparatus

Turning, now, to FIG. 9, a liquid crystal projector according to theinvention is designated 300. The projector 300 includes a housing 301(analogous to housing 9, FIG. 1), an optics portion 302, including lightinput and light output portions 303, 304 (respectively analogous to thelight source, preliminary, e.g. a condensing or collimating lens, andshutter 7 of FIG. 1), and a liquid crystal display 305 (analogous to theimager 2), all preferably located within, coupled to, or supported withrespect to the housing 301, and an electric drive 306 (analogous todrive 18), which may be within, on, or external of the housing 301. Thepurpose of the projector 300 is to project an image or characteristicsof an image formed by the liquid crystal display 305, while the same isdriven by the electric drive 306, onto a projection screen or the like307 (analogous to screen 8).

The liquid crystal display 305, which represents the part of the strip 4immediately aligned in the projection optics 3 for projection of animage therein, is intended selectively to affect (e.g. scatter) and notto affect (e.g. transmit) light incident thereon. For example, theliquid crystal display 305 would include a support medium and/orcontainment medium 310 having one or more layers of plural volumes ofliquid crystal material 311 therein. The support/containment medium 310preferably is formed as a strip of material having a dimension extendinginto the plane of the drawing of FIG. 9 with an edge 312 of such stripbeing seen in FIG. 9. The opposite surfaces 313, 314 of the displaysheet preferably are optically transparent as opposed to being absorbentor reflective. Therefore, when an electric field is applied to aselected portion or area of liquid crystal contained in the display 305,whereby such liquid crystal material becomes effectively transparent,light incident on the display 305 will be transmitted therethroughwithout substantial scattering or absorption. However, light incident onthose portions of the display 305 in which the volumes of liquid crystalmaterial 311 are in the scattering mode described above, or in any eventin the field-off, curvilinearly aligned or distorted structuralorientation, will tend to be isotropically scattered, for example over 2pi radians, as viewed in the planar drawing, or 4 pi steradians in threedimensions (spherical volumes), by such liquid crystal material in themanner described in greater detail above.

Dye, such as non-pleochroic dye, may be included in display 305 to colorlight to produce a colored output. Pleochroic dye may be included in theliquid crystal.

In optics 302 of projector 300, light input portion 303 includes lightsource 319, e.g. a conventional electric lamp or projector lamp, andcollecting or collimating lens 320, and light output portion 304includes projection lens 321 and light control device or lightcontroller 322 to discriminate between light scattered by andtransmitted through liquid crystal display 305. In one embodiment lightcontrol device 322a (FIG. 10) primarily is a mask 323, and in a secondembodiment light control device 322b (FIG. 14) is an aperture 324. Ineither case, light control device 322 selects scattered or transmittedlight for projection. Operation of several projector embodimentsdisclosed herein generally follows the lens formula ##EQU1## Althoughsuch formula applies to thin lenses, it will be apparent to those havingordinary skill in the art that similar properties and operationalconstraints will apply to thick lenses and to multiple lens systems,which are contemplated as included in the invention.

Light source 319 is located at a focal point of the collimating lens 320so that such lens produces a collimated light output 325 directed atliquid crystal display 305. Collimated light 325 incident on portions ofliquid crystal display 305 in field-on, optically transmissivecondition, will be transmitted through display 305 and will continue astransmitted collimated light 326 to projection lens 321. The projectionlens focuses such transmitted collimated light 326 at a focal point 327.

Collimated light 325 incident on liquid crystal material 311 in thefield-off, curvilinearly aligned, distorted, etc., in any eventgenerally isotropic scattering mode or structural alignment, will tendto be scattered. Such scattered light is represented at 328 in FIG. 9.Such scattered light 328 may or may not be received by lens 321. Ifreceived, such scattered light will tend to be projected by lens 321toward light control device 322 but in general will not be focused atthe focal point 327. Scattering of light by liquid crystal display 305occurs primarily due to the difference between the index of refractionof support/containment medium 310 and the extraordinary index ofrefraction of the liquid crystal material itself. (Optical transmissionthrough display 305 without scattering is maximized when the ordinaryindex of refraction of the liquid crystal material and the index ofrefraction of the containment/support medium are matched as closely aspossible--most preferably are equal.)

Although the volumes of liquid crystal material 311 may be arranged inone or more substantially continuous layers throughout liquid crystaldisplay 305, such volumes of liquid crystal material also may bepatterned, whereby discrete sections of liquid crystal display 305 wouldcontain such volumes and other sections would not, thereby providingisolation for respective liquid crystal sections. Electric drive 306 maybe a computer with appropriate power output and/or control circuitry ofconventional design capable of causing the charge applicator 5 to applycharge selectively, as was described above, to produce an electric fieldacross the liquid crystal material 311.

Turning, now, particularly to FIG. 10, the light control device 322aincludes a mask 323 located at the focal point 327 of the projectionlens 321. The collimated light 326 received by the lens 321 is focusedat the focal point 327 and simply is blocked by the mask 323. However,the lens 321 projects the scattered light 328 as light 330 out through alight output opening 331 in the projector 300 housing 301 to form thedesired viewable image on the projection screen 307. To maximize theamount of scattered light collected, the lens 321 in this embodimentshould be as large as is reasonably possible. Additional lenses,mirrors, filters, etc., as may be desired or required, may be employedto complete the function of projecting the light 330 passing out throughthe opening 331 to form the desired image on the screen 307. Using theprojector 300 with the light control device 322a, then, those portionsof the liquid crystal display 305 which are transmissive will appearblack or dark on the screen 307 and those portions which are inscattering mode will appear relatively bright on the screen 307.

In FIG. 11, now, the light control device 322b includes an aperture 324.The projection lens 321 focuses the collimated light 326 at focal point327, which is located in the aperture or at least in a position withrespect to the aperture 324 so as to permit the passage of all orsubstantially all of the light focused thereat through the opening 332for projection onto the screen 307. One or more additional lenses,mirrors or other optical devices may be employed to complete thefunction of projecting such light passing through the aperture 324 ontothe screen 307. However, the scattered light 328 reaching the lens 321is directed as light 330 onto walls 333 of the projector 300 housing 301and/or walls bounding the aperture and, in any event, is blocked frombeing transmitted through the aperture opening 332. Preferably the mask323 (FIG. 10) and the walls 333 are optically absorbent, for exampleincluding black paint, black felt, or other material to absorb lightincident thereon, therefore preventing the reflection of spurious lightback into the interior 334 of the projector housing. In fact, all of theinterior walls of the projector housing 301 may be black or otherwiselight absorbent to minimize spurious light therein.

In operation of the projector 300 employing the light control device322b, then, those portions of the liquid crystal display 305, which arein the field-on, light transmitting mode, will appear bright on thescreen 307; whereas those portions of the liquid crystal display 305which are in the scattering mode will appear relatively dark on thescreen 307. As was mentioned above, the lens formula ##EQU2## generallyapplies. S₁ is the object distance, i.e. the distance of the display 305from the lens 321; S₂ is the image distance, i.e. the distance of thescreen 307 from the lens; and f is the focal length of the lens.

Various conventional support means (not shown) may be employed in theprojector 300 as well as in the other projectors described below withrespect to FIGS. 12A and 13, to support the various components of theprojector in the housing 301 or in any event with respect to suchhousing or with respect to each other. Examples would be a socket forthe lamp of the light source 319, lens holders for the lenses 320, 321,a support frame, such as a holder, or transparent substrate, such as asheet of glass, plastic, Mylar film, etc. for the liquid crystal display305, and so on. Appropriate electrical connections (not shown) alsowould be apparent to those having ordinary skill in the art, such as,for example, power connections to the light source 319 and electricalconnections, represented at 335, between the electric drive 306 and theseveral electrodes of the liquid crystal display 305. Moreover,adjustability of the light output 336 from the projector 300 may beeffected by appropriate adjustability of the size of the mask 323, ofthe opening 331, and/or of the opening 332 in the aperture 324.

Advantages of the projector embodiment of FIG. 10 in particular are theability to use a display 305 that produces a relatively small amount ofscattering in field off condition--therefore the display can berelatively thin; and the ability accurately to control with facility theso-called turn on characteristics of the display and projector usingsame.

The illustrations in FIGS. 12A and 12B demonstrate such advantages ofthe projector 301 of FIG. 10. In FIG. 12A is a profile 340 showing howmuch light may be scattered in respective directions on one side of thedisplay 305 when in field off condition. Much of the scattered light istransmitted through lens 321 and opening 331, but some scattered lightis scattered away from the opening 331 and is blocked by the housingwall 333. As electric field is applied to the liquid crystal display305, the cone of light 341 on the profile 340 will tend to collapse,e.g. as is shown at 341, and the amount of scattered light, i.e.intensity, exiting the opening 331 will increase. The general increasein intensity of projected light through opening 331 as a function ofvoltage or electric field magnitude is represented by curve 343 in FIG.12B, particularly at the lefthand portion 344 of the curve. The changein intensity at curve portion 344 is relatively gradual, and in anyevent over the extent thereof light will be transmitted through theopening 331.

However, when adequate voltage V_(t) is applied to liquid crystal in thedisplay a very rapid transition occurs in the liquid crystal alignment,i.e. so as to become substantially transparent, whereupon thetransmitted light therefrom is focused on the mask 323 and does not passthrough opening 331. Such rapid transition is represented in FIG. 12B atcurve portion 345 which has a much steeper slope than does curve portion344.

Referring to FIG. 13, the preferred embodiment and best mode of theinvention in the form of a liquid crystal projector 350 is shown. Theprojector 350 includes a modified housing 351 containing the projectoroptics 352, including a light input portion 353 and a light outputportion 354. The light input portion 353 includes a light source 319 anda Fresnel lens 355, and the light output portion 354 includes anaperture 356, a reflector 357, and a projection lens 358. The reflector357 and projection lens 358 are positioned in a housing or frame portion360 optically downstream of the aperture 356, which is mounted in thehousing 351. The reflector 357 is provided to fold the optical path ofthe liquid crystal projector 350 and thereby to reduce the size and/orgeneral structural configuration of the projector relative to, forexample, the straight through projector 300 shown in FIG. 9.

The light source 319 is located at one principal point or focus of theFresnel lens 355, and the aperture 356 is located at the oppositeprincipal point or focus 361 of the Fresnel lens 355. Therefore, in theabsence of any optical disturbance, light from the source 319 travelingalong the optical path 362 and received by the Fresnel lens 355 will befocused at the focal point 361 in the aperture or proximate the aperture356. Moreover, the light transmitted through the aperture 356 will bereflected by the reflector 357 toward the projection lens 358 and willbe projected by the latter onto the screen 307, for example to form animage thereon.

The display 305, i.e. that part of strip 4 then being in line to beprojected, e.g. a given frame area of the strip 4, is mounted preferablyin parallel and in proximity to the Fresnel lens 355 and also is mountedin the object plane of the lens 321, i.e. a distance S₁ from the lensaccording to the above formula requirements. Preferably the effect ofthe index of refraction of the display 305 will not detrimentally affectthe light focused by the Fresnel lens 355 at the aperture 356 unlessliquid crystal in the display is in the scattering mode.

In operation of the liquid crystal projector 350, then, the electricdrive 306 operating through the interconnection 335 to the liquidcrystal display 305 applies an electric field, for example, to selectedportions of the display and does not apply an electric field to otherportions. Those portions in which the field is applied will be opticallytransmissive, and the other portions will operate in a scattering mode,as aforesaid. The light transmitted through the display 305 will befocused at the focal point 361 of the Fresnel lens 355 in the aperture356. Such light, moreover, will be reflected by the reflector 357 andprojected by the lens 358 onto the screen 307 to form bright areas of animage thereon. On the other hand, those portions of the liquid crystaldisplay 305 which tend to scatter light, will scatter such lightgenerally isotropically preferably over 4 pi steradians and, in anyevent, substantially most of such light will be scattered away from orso as not to pass through the aperture 356 and instead will be absorbedby the walls or material associated with, lining, etc. the housing 351.

The preferred projector 350 of the invention preferably has colorcapability. Thus, there is located at the aperture 356 a color filtertype device 390, which may be operatively controlled by the electricdrive 306 connected by connection 335a to color or not light transmittedthrough the liquid crystal display 305 and focused by the Fresnel lens355 onto the aperture 356.

The color filter type device 390 is shown in plan view in FIG. 14 havingrespective red, green and blue pie-shape sectors 392R, 392G, 392B. Eachsector preferably is comprised of liquid crystal display material thesame as or similar to that used for the liquid crystal display 355;however, each individual sector of the filter 390 is dyed a respectivecolor. More specifically, the filter 390 may be formed of operationallynematic liquid crystal material contained in plural volumes formed in acontainment medium. Non-pleochroic dye preferably is provided, forexample by imbibition or otherwise, in the liquid crystal materialand/or containment medium in the respective colored sectors. Electrodespositioned on opposite sides of the filter 390 may be energizedselectively by the electric drive 306 to apply an electric potentialacross any one or more of the sectors causing the same to becomegenerally optically transparent, but nevertheless capable of tinting orcoloring light transmitted therethrough. In operation, then, if the redsector 392R had an electric field applied across it to make the samerelatively transparent, while the green and blue sectors 392G, 392B werenot energized, light transmitted through the aperture 356 and projectedby the lens 358 would be tinted or colored red. Similar operation couldoccur by exclusively energizing one of the green or blue sectors 392G,392B to effect green or blue coloring of the projected light. Additivecoloring could occur, too, by energizing two or three of the sectors inthe filter 390. As to those segments 392 which are not energized andoptically transmissive, the same will tend to scatter light whichprimarily will not be collected by the lens 358 for projection onto thescreen 307; although some of such scattered light may be collected andtransmitted, nevertheless the amount of that light would be relativelysmall compared to that transmitted through the energized sector and,accordingly, would have minimal effect on the color projected onto thescreen 307. Also, if desired, an additional undyed sector may beincluded in the filter 390 to facilitate transmitting white light to thelens 358 for projection onto the screen 307. It will be appreciated thatthe electric drive 306 may change selectively the portions or pixels ofthe liquid crystal display 305 and can coordinate the same with selectedoperation of the filter 390 thereby to produce single color ormulticolored images, either still or moving, for projection by the lens358 onto the screen 307.

It will be appreciated that the projector 350 provides control of theoptical characteristics of an image projected onto a relatively largescreen by using a relatively small size light control shutter whichpreferably has one or more different color sectors or segments. Thus, arelatively large area of output light, i.e. the image projected onto thescreen 307, can be chopped or controlled by a relatively small areashutter 390, and using only three different colored sector portions 392of the filter 390, more than three color outputs can be obtained.

Briefly referring to FIG. 15, a liquid crystal display 400 for use withthe several projectors of the invention is shown in conjunction with anelectric drive 306. The display 400 has dye 401 therein. Such dye isrepresented schematically. However, it will be appreciated that such dye401 may be pleochroic dye in the liquid crystal to reduce transmissionand scattering in the field-off condition; may be a non-pleochroic onecolor dye in the liquid crystal or in the contact/support medium tocolor light; or may be several non-pleochroic dyes of several differentcolors located in different portions of the display to provide amulticolor output tending to effect a tinting or coloring form of lightprojected by the projector using such display 400.

Using the circuitry illustrated in FIG. 15 in cooperation with thecharge applicator 5, for example, then, various pixel-like areas, suchas those identified 401R, 401G, 401B in the display 400 selectively canbe addressed to apply or not to apply charge and, thus, an electricfield thereacross. Depending on which pixels are energized and which arenot, light transmitted through the display 400 may be colored so thatthe resulting output of light projected by a projector using suchdisplay 400 are adequately small, the same may in effect be additive inthe coloring effect on the projected light. Accordingly, various colorsmay be produced by having more than one of such pixels energized or notat any given time. Such additive coloring may be considered analogous tothat which occurs in a conventional color television in which selectedcolor dots or pixels are selectively energized, and ordinarily onlythree different colors are required to produce virtually any coloroutput, as is known in this color optics field.

Reference is made to FIG. 16 in which a modified projector 1' isillustrated. Such projector 1' is substantially the same in constructionand operation as the projector 1, except the projector 1' isparticularly useful when employing smectic or operationally smecticliquid crystal material substituted for the nematic liquid crystal 32 inthe volumes 33 within containment medium 31. Ordinarily the smecticliquid crystal structure will align with respect to electric fieldresulting from deposited charge on surface 4S by the charge applicator 5to achieve transmission of light without scattering at those areas ofthe smectic liquid crystal strip (strip 4 with smectic material) wheresuch charge exists. However, erasing of a given image by discharging thestrip ordinarily would be relatively ineffective because smectic liquidcrystal ordinarily is not reversible. Therefore, a heat source 500 isprovided relatively downstream of the projection optics to effect sucherasing of image characteristics on the strip. If necessary, a furtherdischarge roller or rollers 502 may be used to discharge the stripbefore such heating of the same.

Such heat source 500 adequately heats the smectic liquid crystal abovethe smectic nematic transition temperature or to a temperature above theisotropic temperature of the liquid crystal material. As a result, theliquid crystal in the volumes 33 again will have a distorted structurethat will, as in the above described projector 1 with the nematic liquidcrystal, scatter light and will be ready to align with respect toelectric field if a charge is applied again, e.g. by the chargeapplicator. Thus, it will be appreciated that several projectorembodiments described above may employ smectic liquid crystal.

Referring more particularly to operation to distort the smectic liquidcrystal structure after such structure has been aligned with respect toan electric field, the heat source 500 may heat part or all of the strip4 as the strip passes by the heat source. If the heat source heats thestrip to a temperature exceeding the smectic nematic transitiontemperature, such that while above such temperature the smectic liquidcrystal material behaves as nematic liquid crystal material, then whileabove such temperature the structure thereof will undergo distortion ofthe structure thereof to curvilinear alignment as is depicted in FIGS. 3and 5 and is described above.

Above the isotropic temperature of the smectic liquid crystal material,such material loses at least some of the properties of liquid crystal,such as those of structure. However, upon cooling from a temperatureabove isotropic temperature to a temperature below such isotropictemperature the material will regain such structural properties. If suchcooling occurs while the liquid crystal material is within the confinesof a containment medium that contains the material and has a wallsurface capable of imparting the above-described structural distortionto the liquid crystal, then upon such cooling the liquid crystalmaterial will regain the structural characteristics, and the liquidcrystal structure will be distorted, e.g., in the manner described aboveand illustrated in FIGS. 3 and 5.

The time during which the liquid crystal material must be at elevatedtemperature or the time it takes to effect adequate heating of theliquid crystal material to achieve elevated temperature to obtain thedesired curvilinear alignment may be a function of the sizes of thevolumes of the liquid crystal material, the chemical composition of theliquid crystal material, and perhaps other factors. However, the heatsource may be of a size such that it provides adequate heat for suchpurposes essentially regardless of the speed of the strip 4. Thus, heatmay be applied to the strip for a long or a short time, depending on therequirements to effect the distorted alignment or erasing of the liquidcrystal material thereof. Similarly, the time required for the liquidcrystal material adequately to cool to have distorted structure beforebeing subjected to electric field at the charge applicator 5 may beadjusted simply by changing the distance and, thus, the length of thestrip 4, between the heat source 500 and the charge applicator.

Therefore it will be appreciated in this embodiment and in the severalother embodiments of the invention the time of heating to erase or towrite and the time to apply charge and/or to discharte the film 4 orother imager device may be different from the time that a frame is inthe projection optics 3. Such speed or time difference may be achievedby altering the size of the source of heat, charte, etc., by alteringthe size, shape and/or path of the film 4, and/or by providing mechanismto effect some degree of co-directional movement of the film 4 and thesource of heat, charage, etc.

In the liquid crystal projector 1' of FIG. 16 preferably the heat source500 is used to erase the liquid crystal material of the strip 4 as suchstrip passes by the heat source. The charge applicator 5 thenselectively applies charge to the strip 4 to create imagecharacteristics therein. Alternatively, the heat source 500 mayselectively heat only portions of the strip 4 to cooperate with thecharge applicator to create such image characteristics.

Another embodiment of liquid crystal projector 1" that uses smecticliquid crystal material is illustrated in FIG. 17. In the projector 1"the positions of the charge applicator 5 and the heat source 500'relative to the travel direction of the strip 4 are reversed from therelation shown in the projector 1' of FIG. 16. In such embodiment thecharge applicator 5 may be used to apply charge across the entire widthof the strip 4 as the strip passes by the charge applicator to align theliquid crystal structure in parallel. The heat source 500' downstream ofthe charge applicator may be used under control of the computer programdrive 18 selectively to heat only those portions of the liquid crystalstrip 4 intended to scatter light due to distorted structural alignmentthereof. Adequate time for heating and cooling of the liquid crystalmaterial passing the heat source 500' is provided in the mannermentioned below, e.g., according to the length of the heat source 500'and/or of the distance from the heat source 500' to the projectionoptics.

The heat source 500' may be a laser device, for example, of the typeused in laser printers. Such a laser device includes a beam of laserradiation/light of small cross section. The beam rapidly is directed atthe surface of the strip 4 as it is rapidly swept to scan across thatsurface, for example, using a rapidly rotating multi-sided mirror. Amodulator modulates the beam to determine whether or not it is to applyradiation to respective "dot-like" areas of the strip 4 as it is sweptacross the surface. When radiation is so applied to an area of the strip4, such radiation is adequate to effect the desired heating of theliquid crystal material at such area to cause the liquid crystalmaterial to achieve the distorted alignment described above. Other typesof heat sources capable of selectively applying thermal energy torespective areas of the strip alternatively may be used.

In the manner just described, then, it will be appreciated that thecharge applicator 5 effectively erases the strip and the heat source500' selectively writes information to the strip to create thecharacteristics of an image for projection in the manner describedabove. It also will be appreciated that the heat source and the chargeapplicator may be used to cooperate with each other to write informationto selected parts of the strip without erasing all of the strip orwriting to all, i.e., fully across, the strip.

Turning, now, to FIG. 18, a modified projector 600 according to theinvention is illustrated. The projector 600 is similar to the projectors1, 1' and 1" described above. However, in the projector 600 the liquidcrystal member intended to have image characteristics stored therein forprojection is in the form of a rotating disk 602 substituted for theendless strip 4. The disk 602 may be a flat generally transparent diskof material similar to that used in the strip 4 described in detailabove. The disk 602 contains encapsulated liquid crystal material, forexample, operationally nematic material which is adequately supported,e.g., by a support medium, that has adequate strength to maintainrelatively rigid characteristics for accurate writing and projectingfunctions. Exemplary material may be a clear polymer or plastic materialthat has optical characteristics which do not interfere with operationof the liquid crystal material. The encapsulated liquid crystal materialoperates to transmit or to scatter light depending on structuralalignment of liquid crystal material at respective locations therein soas to have created in the disk frames of information or imagecharacteristics that can be projected as above.

In the projector 600, then, a charge applicator 5 may apply electricalcharge to the surface of respective parts of the disk 602 to createinformation or image characteristics for projection. A computer drive 18may be used to determine which portions of the disk are to receiveelectrical charge from the charge applicator 5 to create an image forprojection. As respective frames are brought into alignment with theprojection optics, such information or image is projected to the screen8. After a frame has been projected, the discharger 16' discharges thearea of the disk where the frame had been located, and such area then isready to be written to again by the charge applicator. The discharger16' may be one or more wipers, rollers (e.g., like the discharge rollers16, 17 of FIG. 1), or other means capable of discharging any residualcharge remaining on the disk after projection.

Operation of the projector 600 is generally similar to the operation ofthe projectors 1, 1' and 1" described above. As the disk 602 rotates inthe direction of arrow 604, information or images are written atrespective areas thereof termed "frames". The frames sequentially arerotated into alignment with the projection optics 3 for projectionthereby. A shutter associated with the projection optics may open andclose sequentially so as to present to the screen a series of sequentialimages that can be reconstructed or integrated by an observer in thesame way that conventional motion pictures are so reconstructed orintegrated. After a frame has been projected, it can be erased by thedischarger and the area generally where the frame had been located canbe subsequently re-written with another image by the charge applicator,and so on.

Briefly referring to FIGS. 19 and 20, liquid crystal projectors 600' and600" are shown schematically. Such projectors 600' and 600" are similarto the projector 600 described above with respect to FIG. 18 in thatthey all use a liquid crystal disk on which to form information or imagecharacteristics for projection. However, the disks 602' and 602" of theprojectors 600', 600", respectively, use operationally smectic liquidcrystal material and, accordingly, are similar in operation to theprojectors 1', 1" described in detail above with respect to FIGS. 16 and17.

Thus, the projector 600' includes projection optics 3, a chargeapplicator 5 to write information to the disk 602' and a heat source 500to erase such information after projection thereof. In the projector600" the heat source 500' (e.g., of the laser type) writes informationto the disk 602" for projection by the projection optics 3, and thecharge applicator 5 erases the information after projection. A computerprogram drive 18 may be used in the projectors 600' and 600" todetermine where charge or heat is to be applied to the respective disk602', 602" for writing information thereto, as was described above.

Turning to FIG. 21, a further modified liquid crystal projector 700 isillustrated schematically. The projector 700 uses operationally smecticliquid crystal material and, therefore, is similar to the smecticmaterial projectors described above. Importantly, the projector 700 doesnot apply electrical charge directly to the surface of the smecticliquid crystal film medium 714, such as strip 4 (or equivalently one ofthe disks 602') to achieve parallel alignment of liquid crystalstructure for optical transmission with no scattering or minimumscattering. Rather, a separate pair of electrodes 710, 712 are providedto apply electric field to the encapsulated operationally smectic liquidcrystal material as it is moved past the electrodes; and such electricfield causes the desired parallel alignment of liquid crystal structure.Due to the memory capability of the smectic liquid crystal material, theparallel aligned smectic liquid crystal structure remains so aligneduntil subsequently caused to be in distorted alignment in response toheat input as was described above. Advantageously the smectic film 714does not have to carry its own electrode to hold the surface charge orto undergo and to maintain parallel structural alignment of the smecticliquid crystal material. This is due to the bulk structural storagecapability of the encapsulated smectic liquid crystal material, as wasdescribed below.

The various principles disclosed with respect to a particular embodimentof liquid crystal projector described herein may be used with one ormore of the other embodiments hereof in accordance with the spirit andscope of the invention. Various equivalent parts and methods ofoperation may be employed within the spirit and scope of the invention.

It will be appreciated that the invention embodies several methods withwhich various disclosed and other apparatus may be used. Summarizing, animage is applied to and is stored by liquid crystal material in one partof a liquid crystal member. Relative movement or effective movementoccurs between projection optics and such one part of the liquid crystalmember so that such optics can be used to project the image. A furtherimage can be applied to and stored by another part of the liquid crystalmember for subsequent projection by the projection optics. Such furtherimage may be applied to the other part of the liquid crystal memberwhile the first image is being projected; and the speed with which animage is applied to the liquid crystal member or is erased therefrom maybe different than the relative projection speed, i.e., the time periodmeasured from the commencing of projecting of one image until thecommencing of projecting of the next image by the projection optics. Theliquid crystal member serves as a transfer medium to receive and tostore images and to convey the images into the projection optics forprojection or to store the images as the projection optics effectivelymoves relative to the liquid crystal member so as to projectsequentially the images contained therein.

STATEMENT OF INDUSTRIAL APPLICATION

The invention may be used, inter alia, to project a light image ofcharacteristics created in a liquid crystal optical display.

I claim:
 1. A liquid crystal moving picture projector comprising aliquid crystal imager means for creating characteristics of an image,andprojection optics means for projecting images sequentially created bythe imager, said imager means including a liquid crystal materialcapable of temporarily storing information at respective areas thereofto create image characteristics capable of being projected sequentiallyby said projection optics means, said liquid crystal material comprisinga disk-like structure of liquid crystal in a containment medium,
 2. Theprojector of claim 1, further comprising means for effecting relativemovement between said disk-like structure and said projection opticsmeans thereby sequentially to bring respective information to saidprojection optics for projection thereby.
 3. A liquid crystal movingpicture projector comprising a liquid crystal imager means for creatingcharacteristics of an image, andprojection optics means for projectingimages sequentially created by the imager, said imager means including aliquid crystal material capable of temporarily storing information atrespective areas thereof to create image characteristics capable ofbeing projected sequentially by said projection optics means, furthercomprising input means for at least one of writing or erasinginformation with respect to said liquid crystal material for projectionby said projection optics means, said input means comprising means foreffecting such writing or erasing at a speed different than the speedwith which respective areas of said liquid crystal material areprojected by said projection optics means.
 4. A projector,comprisingprojecting means for projecting respective images, asubstantially continuous transfer medium means for conveying to saidprojecting means respective sets of image characteristics for projectionby said projecting means, said transfer medium means having a storagecapability for storing at plural locations thereof respective sets ofimage characteristics for projection and being capable of beingre-written at such respective areas with the same or differentrespective sets of image characteristics, and said transfer medium meanscomprising liquid crystal material having structural characteristicsresponsive to a prescribed input to create such image characteristics,said liquid crystal material comprising a disk-like structure of liquidcrystal in a containment medium,
 5. A projector, comprisingprojectingmeans for projecting respective images, a substantially continuoustransfer medium means for conveying to said projecting means respectivesets of image characteristics for projection by said projecting means,said transfer medium means having a storage capability for storing atplural locations thereof respective sets of image characteristics forprojection and being capable of being re-written at such respectiveareas with the same or different respective sets of imagecharacteristics, said transfer medium means comprising liquid crystalmaterial having structural characteristics responsive to a prescribedinput to create such image characteristics, and further comprising inputmeans for at least one of writing or erasing information with respect tosaid liquid crystal material for projection by said projection opticsmeans, said input means comprising means for effecting such writing orerasing at a speed different than the speed with which respective areasof said liquid crystal material are projected by said projection opticsmeans,
 6. A method of projecting plural images in sequence,comprising:creating an image or characteristics of an image in a liquidcrystal material, storing such image in such liquid crystal material,directing light at such liquid crystal material, projecting such imageas a function of light transmitted through or scattered by such liquidcrystal material, and creating a further image in such liquid crystalmaterial for subsequent projection, wherein such liquid crystal materialhas structural storage properties, and said storing comprising causingthe structure of such liquid crystal material to assume and to maintaina prescribed structural alignment in the absence of externally appliedinput, such liquid crystal material comprising liquid crystal in acontainment medium that in the absence of prescribed input tends todistort the liquid crystal structure to increase scattering orabsorption of incident light, and said storing comprising applyingthermal energy to the liquid crystal to heat the same above atemperature which allows the same to undergo structural distortion andcooling the liquid crystal to maintain such distortion absentapplication of further prescribed input thereto,
 7. A method ofprojecting plural images in sequence, comprising:creating an image orcharacteristics of an image in a liquid crystal material, storing suchimage in such liquid crystal material, directing light at such liquidcrystal material, projecting such image as a function of lighttransmitted through or scattered by such liquid crystal material, andcreating a further image in such liquid crystal material for subsequentprojection, wherein such liquid crystal material comprises a rotatabledisk-like structure of liquid crystal in a containment medium, saidcreating steps comprising creating images at plural areas of suchdisk-like structure, and further comprising rotating such disk-likestructure sequentially to move such respective areas into projectingmeans sequentially to project such images,
 8. A method of projectingplural images in sequence, comprising:creating an image orcharacteristics of an image in a liquid crystal material, storing suchimage in such liquid crystal material, directing light at such liquidcrystal material, projecting such image as a function of lighttransmitted through or scattered by such liquid crystal material, andcreating a further image in such liquid crystal material for subsequentprojection, wherein the liquid crystal material comprises liquid crystalin a containment medium, and said creating comprises applying electricfield to the liquid crystal material to cause alignment of the liquidcrystal structure with respect to such field, and further comprisingerasing such image by applying thermal energy to the liquid crystalmaterial to enable the structure alignment of the liquid crystal toassume a distorted alignment under the influence of such containmentmedium,
 9. A method of projecting plural images in sequence,comprising:creating an image or characteristics of an image in a liquidcrystal material, storing such image in such liquid crystal material,directing light at such liquid crystal material, projecting such imageas a function of light transmitted through or scattered by such liquidcrystal material, and creating a further image in such liquid crystalmaterial for subsequent projection, wherein the liquid crystal materialcomprises liquid crystal in a containment medium, and said creatingcomprises applying thermal energy to the liquid crystal material toenable the structural alignment of the liquid crystal to assume adistorted alignment under the influence of such containment medium, andfurther comprising erasing such image by applying electric field to theliquid crystal material to cause alignment of the liquid crystalstructure with respect to such field.